1. Field of the Invention
The present invention relates to an image encoding device and an image decoding device which perform image processing.
2. Description of the Prior Art
Conventionally, it is always necessary at the decoding side that the analysis of VOP (Video Object Plane) header information be preceded by analysis of a VOP start code, a modulo time base and a VOP time increment contained in each VOP header, because no distinction can be made between VOPs not to be analyzed (information to be decimated in the case of a low speed shot of an image signal) and those to be analyzed (information not to be decimated). Accordingly, the decoding process is inevitably cumbersome and prone to low accuracy.
For decoding and synthesizing encoded signals respectively corresponding to a subject, a background, a logo and similar objects which form a pictorial image, it is necessary that each object be added with a synthesizing timing signal (information representing absolute time) necessary for decoding and synthesizing the object. Without such absolute time information, the image decoding device cannot synthesize the object, and hence it is incapable of image reconstruction. In short, in the case of generating one pictorial image from a plurality of objects including those having no absolute time information, it is impossible with the prior art to combine objects having the required information with those having no such information.
Moreover, the bit length of the modulo time base increases until the next GOV header is multiplexed—this raises a problem that the bit length of the modulo time base keeps on increasing when the GOV header, which is an option, is not multiplexed.